Blueprint of Life Topic 22: Cloning Biology in Focus, HSC Course Glenda Childrawi, Margaret Robson and Stephanie Hollis

DOT POINT(s) identify how the following current reproductive techniques may alter the genetic composition of a population: artificial insemination artificial pollination Cloning (we will discuss this today) Process information from secondary sources to describe a methodology used in cloning

Introduction Taking the ‘unknown’ out of selective breeding Selective breeding relies to some extent on ‘trial and error’— hoping that the desired combination of favourable genes ends up in some individuals, which can then be selected and interbred. www.bbc.co.uk

Introduction Two modern-day technologies that take care of the trial and error nature of selective breeding are cloning and genetic engineering (genetically modifying organisms). technode.com

Genetic Engineering Genetic engineering involves adding a desirable gene to the DNA of an individual or removing and substituting a gene and then ensuring that, when it reproduces, it passes this gene on with all of its other genes, creating a transgenic species. www.earthtimes.org

Types of Cloning Cloning involves the production of an individual that is genetically identical to one that already exists. There are three types of cloning: someinterestingfacts.net

Types of Cloning 1. Reproductive cloning involves creating a genetically identical, fully developed organism, using a cell (or a few cells) from another mature organism. This whole organism cloning is a form of asexual reproduction and so it is considered to be a reproductive technology. www.bioethics.ac.uk

Types of Cloning Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly was created by reproductive cloning technology. www.freewebs.com

Types of Cloning In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. evolution.berkeley.edu

Types of Cloning The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth www.geneticsandsociety.org

Types of Cloning Dolly or any other animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. www.odec.ca

Types of Cloning Dolly's success is truly remarkable because it proved that the genetic material from a specialized adult cell, such as an udder cell programmed to express only those genes needed by udder cells, could be reprogrammed to generate an entire new organism. Before this demonstration, scientists believed that once a cell became specialized as a liver, heart, udder, bone, or any other type of cell, the change was permanent and other unneeded genes in the cell would become inactive. www.geneticsandsociety.org

Types of Cloning 2. Therapeutic cloning involves using cells from an individual to produce a cloned early embryo, which is then used as a source of embryonic stem cells to replace degenerating adult tissues or to repair damage. science.howstuffworks.com

Types of Cloning The purpose of therapeutic cloning is not to produce a new animal or plant, but to provide a source of cells that can be used to repair adult tissue that has been damaged (e.g. by degenerative disease). www.arhp.org

Types of Cloning Stem cells are important to biomedical researchers because they can be used to generate virtually any type of specialized cell in the human body. Stem cells are extracted from the egg after it has divided for 5 days. cloningbasicsforkids.wordpress.com

Types of Cloning The extraction process destroys the embryo, which raises a variety of ethical concerns. Many researchers hope that one day stem cells can be used to serve as replacement cells to treat heart disease, Alzheimer's, cancer, and other diseases. commons.wikimedia.org

Types of Cloning 3. Gene cloning occurs at a cellular level and involves producing identical copies of a gene. It is an important step in the process of genetic engineering. www.abfrontier.com

Cloning—a contentious issue? Cloning is not a new phenomenon— identical twins are naturally produced genetic clones and occur in every animal species studied for this phenomenon. Cloning is also common in plants—botanists have been using cuttings, the splitting of bulbs and other forms of asexual reproduction to propagate plants over many centuries. multiples.about.com

Cloning—a contentious issue? Animals were first cloned a century ago when two-celled embryos of sea urchins and salamanders were split. Bananas are also clones of each other and vastly different from their ancestral stock. They have a very limited gene pool. firstivf.net

Cloning—a contentious issue? Embryo-splitting leading to multiple births occurs naturally and can be fairly easily replicated in a laboratory. However, cloning from adult cells (of living or even deceased organisms) is not a phenomenon that occurs in nature. www.hoglezoo.org

Advantages of Cloning Cloning is used as a form of selective breeding once an ‘ideal’ hybrid has been obtained. Cloning reduces the ‘unknown’ element in selective breeding— the characteristics being bred can be precisely controlled. This type of artificial selection occurs in growing seedless grapes and bananas. endtimeinfo.com

Disadvantage of Cloning If all members of a species are identical, the population is less likely to survive sudden environmental changes and would be vulnerable to foreign pathogens. If many clones are produced from one parent organism, the effect would be to reduce the variability of the population as all organisms would have identical DNA. www.immortalhumans.com

Natures Way In nature, genes are conserved by evolution only if they serve an essential function for the organism. For example, the genes for cytochromes (proteins that are essential for chemical respiration) are conserved because, if they are altered by mutation, the individual cannot survive. Therefore a mutation in such a gene, which alters the protein, will not be passed on. evolution.berkeley.edu

Activity/Homework -Students to complete DOT Point 5.1 a